Sports Tracker - No longer maintained by Nokia, now maintained by a Third Party. You can log your workout path, export that to view it later on Google Earth on your PC. You can get your instantaneous speed, direction, location etc.. Even the title of the song playing while you move gets saved! (The earlier version maintained by nokia used to crash when used simultaneously with the music player playing music over a bluetooth headset, but this problem is no longer there in the new version)

Cinemax - Check show timings across the chain, book tickets (Java based). Ticket booking failed when I first tried it - had to call the customer care and get a refund.

ICICI iMobile - Access your bank account, transfer money, pay bills (Java based). First used this on my Nokia 5700 - worked well on that. It was a whole year after I switched to Nokia 5800 that ICICI upgraded their app which now works nicely on 5800.